4.21% is the change from 831 to 866
Calculation steps:
[( 866 - 831 ) ÷ 831] x 100 = 4.21%
Formula
Percentage change = [(866 - 831) / 831] x 100
Subtract the new number by the original number
866 - 831 = 35
35 ÷ 831 = 0.0421179302045728
0.0421179302045728 x 100 = 4.21%